Variable power adjustment access method in CDMA mobile communication system

ABSTRACT

An access method for adjusting variable power in the CDMA mobile communication system includes obtaining acquisition information through receiving a prefix of a physical random access channel, and an access prefix and a conflict detection prefix of a physical common packet channel and evaluating quality, respectively; performing precise control of transmission power of a message section of the physical random access channel, and the conflict detection prefix, a power control prefix, and a message section of the physical common packet channel; transmitting a control indication of the precise control; and transmitting the message section of the physical random access channel, and the conflict detection prefix, the power control prefix, and the message section of the physical common packet channel by using a value among a plurality of power bias values.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of International Application No.PCT/CN02/00098, filed on Feb. 20, 2002, which claims priority to ChineseApplication No. 01 1 26300.8, filed on Jul. 20, 2001. The contents ofboth applications are incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

The invention relates to the access of the mobile communication system,particularly, relates to an access method for the variable poweradjustment. The said method supports the physical random access channel(PRACH) and the physical common packet channel (PCPCH) of the up link,the acquisition indication channel (AICH), the access prefix acquisitionindication channel (AP-ACH), and the conflict detection/channelassignment indication channel (CD/CA-ICH) of the down link by moreprecise power control.

BACKGROUND OF THE INVENTION

In the access technology of the radio communication, there is an accessmethod based on the fast indication. The burst data of the access canoften be divided into several sections, the next section of theinformation is transmitted normally only when the responses of the datain the preceding sections (For example, an acquisition response, and thelike) have been received. Normally, this type of responses only hasresponses with two values of 1 and −1, or with three values of 1, −1,and 0. Wherein, only one value, for example 1, is used for theindication acquired successfully and allowed to access. Thus, the moreprecise control function can not be sufficient.

Please refer to FIG. 1 and FIG. 2, in the access of the physical randomaccess channel (PRACH) and the physical common packet channel (PCPCH) ofthe up channels in WCDMA, the fast indication method is used forindicating the prefix acquisition situation. For the physical randomaccess channel (PRACH), the acquisition indication channel (AICH) isused to indicate the acquisition on the down link. For PCHCH, the accessprefix acquisition indication channel (AP-ACH) and the conflictdetection/channel assignment indication channel (CD/CA-ICH) are used.For the physical random access channel (PRACH), a value evaluated by theopen loop power is firstly used by the user equipment as thetransmission prefix of the initial transmission power. If theacquisition indication information of the down link acquisitionindication channel (AICH) has not been received (or the receivedacquisition indication information is 0), then another prefix willcontinuously be transmitted subsequently by adding power ΔP0. If thereceived acquisition indication is −1, then it will exit the procedureand report to the upper layer. If the received acquisition indication is1, then the information section will be transmitted by using a preamblepower bias ΔPp-m corresponding to the last successful access.

In this way, because an error may be reach +/−12 dB under an extremesituation of the open loop power evaluation, and considering thethroughput of the physical random access channel (PRACH), ΔP0 being nottaken very small, and the affect of the channel fading, AP power whichis accessed successfully at last and the acquisition probability at thesaid power may change significantly. If this is taken as a referencepower to transmit the signals of the information section by increasingthe power bias ΔPp−m (once this parameter is assigned by the high layer,all of the user equipment will use this fix parameter in a long periodunless reassigning), the variation range of the power of the informationsection may also be very large, causing the comprehensive performance ofaccessing the entire physical random access channel (PRACH) worse.

The access procedure for the physical common packet channel (PCPCH) isslightly similar as that of the physical random access channel (PRACH),a transmitted access prefix AP is evaluated firstly by the userequipment based on the open loop power. If the acquisition indicationinformation of the down link prefix acquisition indication channel(AP-AICH) is not received (or the acquisition indication is 0), then theprefix will continuously be transmitted by using power bias ΔP0. If thereceived acquisition indication is 1, then the conflict detection prefix(CD-P) will be transmitted by using the same power.

If the corresponding conflict detection prefix (CD-P) is not received inthe conflict detection/channel assignment indication channel(CD/CA-ICH), then the procedure will be exited and reported to the upperlayer. If it is received, then the power control prefix and the messagesection are transmitted by using the power bias of ΔPp−m.

For the same reason as that for accessing the physical random accesschannel (PRACH), AP power which is accessed successfully at last of thephysical common packet channel (PCPCH) and the acquisition probabilitybased on the said power may change significantly. In this way, theconflict detection transmitted subsequently and the power control prefixand the initial power of the message section will also changesignificantly. Thus, it causes the comprehensive performance of theentire link worse.

The frame format of the acquisition indication channel (AICH) in WCDMAis shown in FIG. 3, wherein,

$a_{j} = {\sum\limits_{s = 0}^{15}\;{{AI}_{s}b_{s,j}}}$

The value of acquisition indication AI is taken as 1, 0, and −1 based onthe result of the acquisition. S represents the sequence number of thecharacteristic code. See Table 1 for the value of bs and j (Table 1 is acharacteristic code table of the acquisition indication channel):

TABLE 1 s b_(s,0), b_(s,1) . . . , b_(s,31) 0 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 2 1 1 1 1 −1 −1−1 −1 1 1 1 1 −1 −1 −1 −1 1 1 3 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1 −1 −1 1 11 1 4 1 1 1 1 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 1 1 5 1 1 −1 −1 1 1 −1 −1−1 −1 1 1 −1 −1 1 1 1 1 6 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 1 1 1 1 1 1 71 1 −1 −1 −1 −1 1 1 −1 −1 1 1 1 1 −1 −1 1 1 8 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 −1 −1 9 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 −1 −1 10 1 1 1 1−1 −1 −1 −1 1 1 1 1 −1 −1 −1 −1 −1 −1 11 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1−1 −1 1 1 −1 −1 12 1 1 1 1 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 −1 −1 13 1 1−1 −1 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1 −1 −1 14 1 1 1 1 −1 −1 −1 −1 −1 −1−1 −1 1 1 1 1 −1 −1 15 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1 1 1 −1 −1 −1 −1 sb_(s,0), b_(s,1) . . . , b_(s,31) 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 −1 −11 1 −1 −1 1 1 −1 −1 1 1 −1 −1 2 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1 −1 −1 3 −1−1 −1 −1 1 1 1 1 −1 −1 −1 −1 1 1 4 1 1 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 5−1 −1 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1 6 1 1 −1 −1 −1 −1 −1 −1 −1 −1 1 1 11 7 −1 −1 −1 −1 1 1 −1 −1 1 1 1 1 −1 −1 8 −1 −1 −1 −1 −1 −1 −1 −1 −1 −1−1 −1 −1 −1 9 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 10 −1 −1 1 1 1 1 −1 −1−1 −1 1 1 1 1 11 1 1 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1 12 −1 −1 −1 −1 −1 −11 1 1 1 1 1 1 1 13 1 1 −1 −1 1 1 1 1 −1 −1 1 1 −1 −1 14 −1 −1 1 1 1 1 11 1 1 −1 −1 −1 −1 15 1 1 1 1 −1 −1 1 1 −1 −1 −1 −1 1 1

Thus, it is stipulated in the current protocol that the acquisitionindication channel can only have three types of indications of 0, 1, and−1 for a certain characteristic code. Wherein, only the acquisitionindication “1” is used to indicated that the accessing is allowed,however, more precise power control information cannot be provided.

The same format as that used for the acquisition indication channel(AICH) can be used to transmit the prefix acquisition indication channel(AP-ACH).

For the conflict detection/channel assignment indication channel(CD/CA-ICH),

$a_{j} = {{\sum\limits_{i = 0}^{15}\;{{CDI}_{i} \times b_{s_{i},j}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k} \times b_{s_{k},j}}}}$wherein, CDIi and CAIk generate the value, refer to Table 2 (Table 2 isa generation table for CDIi and CAIi in the conflict detection/channelassignment indication channel);

TABLE 2 Conflict detection prefix i Channel transmitted characteristicassignment Characteristic by user code sequence code equipment i CDI_(i)s_(i) number k CAI_(k) s_(k) 0 +1/0 1 0 +1/0 0 1 −1/0 1 −1/0 2 +1/0 3 2+1/0 8 3 −1/0 3 −1/0 4 +1/0 5 4 +1/0 4 5 −1/0 5 −1/0 6 +1/0 7 6 +1/0 127 −1/0 7 −1/0 8 +1/0 9 8 +1/0 2 9 −1/0 9 −1/0 10 +1/0 11 10 +1/0 10 11−1/0 11 −1/0 12 +1/0 13 12 +1/0 6 13 −1/0 13 −1/0 14 +1/0 15 14 +1/0 1415 −1/0 15 −1/0

Therefore, only two indications of 1 and −1 are used to indicate thatthe conflict detection has been acquired, and it is unable to provide tothe user equipment the more precise control indication.

Because the power fluctuation range of the current physical randomaccess channel (PRACH) and physical common packet channel (PCPCH) isvery large when acquiring, however, only one indication is used forpermitting access when the acquisition is successful, thus, it causesthe fluctuation range of the subsequent information transmission power,which takes the said power as a power bias reference, of the subsequentsections also being very large, and causing the whole access performancedegrading.

SUMMARY OF THE INVENTION

The object of the invention is to aim at the above disadvantagesexisting in the access transmission of code division multiple access andto provide an access method having variable power adjustment to increasethe comprehensive performance of the entire system.

In order to realize the above object, the following technical scheme isemployed in the invention:

An access method for the variable power adjustment in the code divisionmultiple access mobile communication system of the invention, the saidmethod is based on the base station and the user equipment, theacquisition information is obtained by the base station throughreceiving on the up link the prefix of the physical random accesschannel, the access prefix of the physical common packet channel and theconflict detection prefix and evaluating the quality, respectively; theprecise control of the transmission power of the subsequent messagesection of the physical random access channel, conflict detection prefixof the physical common packet channel, and the power control prefix, themessage section are obtained based on the quality evaluation value; thecontrol indication of the said precise control is transmitted via thedown link acquisition indication channel, access prefix acquisitionindication channel, and conflict detection/channel assignment indicationchannel; and after receiving the said power control indication by theuser equipment, the subsequent message section of the physical randomaccess channel, conflict detection prefix of the physical common packetchannel, and the power control prefix, the message section aretransmitted by using a value among a plurality of power bias values.

Because after the above method being employed by the invention, theentire system can satisfy different functions, particularly, thefunctions of the transmission power being controlled more precisely, andthe receive performance of the link being improved, it is indicatedspecifically as follows:

1. The accuracy of the power control of the up link transmitted physicalrandom access channel and physical common packet channel, and thesuccessful probability can be improved.

2. The average transmission power of the physical random access channeland physical common packet channel for achieving the same accessperformance can be saved, the interference to other channel can bedecreased, and the capacity of the entire system can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration diagram of an access procedure of the physicalrandom access channel of WCDMA;

FIG. 2 is an illustration diagram of an access procedure of the physicalcommon packet channel of WCDMA; and

FIG. 3 is an illustration of a frame format for acquiring the indicationchannel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

By analyzing the deficiencies in the aspect of the access acquisitionindication of the prior schemes, a method of the invention provides ascheme, in which, the power transmission can be adjusted more preciselyon the up link channels of the physical random access channel (PRACH)and the physical common packet channel (PCPCH), and more precise accessacquisition indication can be provided on the corresponding down linkacquisition indication channel (AICH), AP-acquisition indication channel(AICH), and conflict detection/channel assignment indication channel(CD/CA-ICH).

The method of the invention is based on the base station and the userequipment, the said method is based on the base station and the userequipment, the acquisition information is obtained by the base stationthrough receiving on the up link the prefix of the physical randomaccess channel, the common access prefix of the physical common packetchannel and the conflict detection prefix and evaluating the quality,respectively; the precise control of the transmission power of thesubsequent message section of the physical random access channel,conflict detection prefix of the physical common packet channel, and thepower control prefix, the message section are obtained based on thequality evaluation value; the control indication of the said precisecontrol is transmitted via the down link acquisition indication channel,access prefix acquisition indication channel, and conflictdetection/channel assignment indication channel; and after receiving thesaid power control indication by the user equipment, the subsequentmessage section of the physical random access channel, conflictdetection prefix of the physical common packet channel, and the powercontrol prefix, the message section are transmitted by using a valueamong a plurality of power bias values.

Please refer to FIG. 3, the format of the acquisition indication channeland access prefix acquisition indication channel having the said precisecontrol indication is:

$a_{2k} = {\sum\limits_{s = 0}^{15}\;{{AI}_{1,s}{P_{s}(k)}}}$${a_{{2k} + 1} = {\sum\limits_{s = 0}^{15}\;{{AI}_{2,s}{P_{s}(k)}}}},{k = 0},{{1\mspace{14mu}\ldots\mspace{14mu} 15};}$

wherein, Ps(k) is a prefix characteristic code, please refer to Table 3for its value (Table 3 is an acquisition indication channelcharacteristic code table employed in the invention):

TABLE 3 prefix characteristic value of N code 0 1 2 3 4 5 6 7 8 9 10 1112 13 14 15 P₀(n) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 P₁(n) 1 −1 1 −1 1 −1 1−1 1 −1 1 −1 1 −1 1 −1 P₂(n) 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1P₃(n) 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 P₄(n) 1 1 1 1 −1 −1 −1 −11 1 1 1 −1 −1 −1 −1 P₅(n) 1 −1 1 −1 −1 1 −1 1 1 −1 1 −1 −1 1 −1 1 P₆(n)1 1 −1 −1 −1 −1 1 1 1 1 −1 −1 −1 −1 1 1 P₇(n) 1 −1 −1 1 −1 1 1 −1 1 −1−1 1 −1 1 1 −1 P₈(n) 1 1 1 1 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 P₉(n) 1 −11 −1 1 −1 1 −1 −1 1 −1 1 −1 1 −1 1 P₁₀(n) 1 1 −1 −1 1 1 −1 −1 −1 −1 1 1−1 −1 1 1 P₁₁(n) 1 −1 −1 1 1 −1 −1 1 −1 1 1 −1 −1 1 1 −1 P₁₂(n) 1 1 1 1−1 −1 −1 −1 −1 −1 −1 −1 1 1 1 1 P₁₃(n) 1 −1 1 −1 −1 1 −1 1 −1 1 −1 1 1−1 1 −1 P₁₄(n) 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1 1 1 −1 −1 P₁₅(n) 1 −1 −1 1−1 1 1 −1 −1 1 1 −1 1 −1 −1 1

The values of AI₁ and AI₂ can be taken as 0, 1, and −1, nine controlindications can be produced by combining AI₁ and AI₂. The format of thesaid conflict detection/channel assignment indication channel is:

$a_{2l} = {{\sum\limits_{i = 0}^{15}\;{{CDI}_{i,1}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k,1}{P_{Sk}(l)}}}}$${a_{{2l} + 1} = {{\sum\limits_{i = 0}^{15}{{CDI}_{i,2}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k,2}{P_{Sk}(l)}}}}},{1 = 0},{{1\mspace{14mu}\ldots\mspace{14mu} 15};}$

wherein,

CDI₁, CAI₂, can be taken as 0, 1, and −1.

The definitions of T1, T₀, and T⁻¹ are as follows:T₁={(1, 1), (1, 0), (0, 1)};T₀={(0, 0), (1, −1), (−1, 1)};T⁻¹={(−1, −1), (−1, 0), (0, −1)}.

In the power adjustment of the messages of the said physical randomaccess channel,

when the acquisition indications of the received down link acquisitionindication channel are (0, 0), (1, −1), (−1, 1), then the prefixes willbe transmitted by using continuously the power bias ΔP0;

when (0, −1), (−1, 0), (−1, −1) are received, then the access will beexited and reported to the upper layer;

when (1, 1) is received, then the messages will be transmitted by usingthe power bias ΔPp−m;

when (1, 0) is received, then the messages will be transmitted by usingthe power bias ΔPp−m+ΔP1;

when (0, 1) is received, then the messages will be transmitted by usingthe power bias (ΔPp−m+2*ΔP1).

After the down link access prefix acquisition indication channel isreceived by the said physical common packet channel,

when the access prefix acquisition indications received by the userequipment on the down link are (0, 0), (1, −1), (−1, 1), then the accessprefixes will be transmitted by using continuously the power bias ΔP0;

when (0, −1), (−1, 0), (−1, −1) are received, then the access will beexited and reported to the upper layer;

when (1, 1) is received, then the messages will be transmitted by usingthe same power bias;

when (1, 0) is received, then the messages will be transmitted by usingthe power bias ΔP1;

when (0, 1) is received, then the messages will be transmitted by usingthe power bias (2*ΔP1).

After the indications of the transmission power bias indicated by theconflict detection/channel assignment indication channel is received bythe said physical common packet channel, if it is in T₀ set, then theaccess procedure will be exited; if those in T₁ or T⁻¹ set are received,then an acquisition will be indicated, and the power biases of thesubsequent power control prefixes and the messages will be determined bythe specific values of T₁ or T⁻¹; when the received indication is (1, 1)or (−1, −1), then the power control prefixes and messages will betransmitted by using the power bias ΔPp−m; if the received indication is(1, 0) or (−1, 0), then the power control prefixes and messages will betransmitted by using the power bias (ΔPp−m+ΔP1); if the receivedindication is (0, 1) or (0, −1), then the power control prefixes andmessages will be transmitted by using the power bias (ΔPp−m+2*ΔP1).

Similarly, the frame format in FIG. 3 is employed, however, wherein

$a_{2k} = {\sum\limits_{s = 0}^{15}\;{{AI}_{1,s}{P_{s}(k)}}}$${a_{{2k} + 1} = {\sum\limits_{s = 0}^{15}\;{{AI}_{2,s}{P_{s}(k)}}}},{k = 0},{{1\mspace{14mu}\ldots\mspace{14mu} 15};}$

The values of AI1 and AI2 can be taken as 0, 1, and −1. In this way, Thevalue AI is composed of (AI1, AI2), and total 9 combinations arepossible: (0, 0), (0, 1), (0, −1), (1, 0), (1, 1), (1, −1), (−1, 0),(−1, 1), and (−1, −1). In this way, sufficient acquisition indicationscan be transmitted to use for more precise power control or other usage.

For AP-acquisition indication channel (AICH), a modification method sameas that of the acquisition indication channel (AICH) can be used.

For the conflict detection/channel assignment indication channel(CD/CA-ICH),

$a_{2l} = {{\sum\limits_{i = 0}^{15}\;{{CDI}_{i,1}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k,1}{P_{Sk}(l)}}}}$${a_{{2l} + 1} = {{\sum\limits_{i = 0}^{15}{{CDI}_{i,2}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k,2}{P_{Sk}(l)}}}}},{1 = 0},{{1\mspace{14mu}\ldots\mspace{14mu} 15};}$

The generation of CDIi (composed of (CDIi, 1, CDIi, 2)) and CAIk(composed of (CAIk, 1, CAIk, 2)) can be defined in the following Table 4(Table 4 is a generation table for CDIi and CAIi in the conflictdetection/channel assignment indication channel employed in theinvention):

TABLE 4 Conflict detection prefix i charac- Channel transmitted teristicassignment Characteristic by user code sequence code equipment i CDI_(i)s_(i) number k CAI_(k) s_(k) 0 T₁/T₀ 1 0 T₁/T₀ 0 1 T⁻¹/T₀ 1 T⁻¹/T₀ 2T₁/T₀ 3 2 T₁/T₀ 8 3 T⁻¹/T₀ 3 T⁻¹/T₀ 4 T₁/T₀ 5 4 T₁/T₀ 4 5 T⁻¹/T₀ 5T⁻¹/T₀ 6 T₁/T₀ 7 6 T₁/T₀ 12 7 T⁻¹/T₀ 7 T⁻¹/T₀ 8 T₁/T₀ 9 8 T₁/T₀ 2 9T⁻¹/T₀ 9 T⁻¹/T₀ 10 T₁/T₀ 11 10 T₁/T₀ 10 11 T⁻¹/T₀ 11 T⁻¹/T₀ 12 T₁/T₀ 1312 T₁/T₀ 6 13 T⁻¹/T₀ 13 T⁻¹/T₀ 14 T₁/T₀ 15 14 T₁/T₀ 14 15 T⁻¹/T₀ 15T⁻¹/T₀

Three sets are defined, for example:T1={(1, 1), (1, 0), (0, 1)};T0={(0, 0), (1, −1), (−1, 1)};T−1={(−1, −1), (−1, 0), (0, −1)};

The conditions of the sets may be those, but it is not limited.

AI indications with more values can be received by the user equipment inthe channel of the up link physical random access channel (PRACH). Thepower adjustment can be performed more precisely to transmit thesubsequent messages based on theses received indications. One adjustmentscheme is that after Preamble being transmitted by the user equipment,if the acquisition indications of the received down link acquisitionindication channel (AICH) are (0, 0), (1, −1), (−1, 1), then Preamblewill be transmitted by using continuously the power bias ΔP0. If (0,−1), (−1, 0), (−1, −1) are received, then the procedure will be exitedand the upper layer will be reported to. If (1, 1) is received, then themessages are transmitted by using the power bias ΔPp−m. If (1, 0) isreceived, then the messages will be transmitted by using the power bias(ΔPp−m+ΔP1). If (0, 1) is received, then the messages will betransmitted by using the power bias (ΔPp−m+2*ΔP1).

If more acquisition power adjustment indications are to be added, theother received information can be defined as the power adjustmentindications, for example, (1, −1), (−1, 1), and the like.

Similarly, in the up link physical common packet channel (PCPCH), whenthe indications (0, 0), (1, −1), (−1, 1) of AP-AI are received by theuser equipment on the down link, then AP will be transmitted by usingcontinuously the power bias ΔP0.

If (0, −1), (−1, 0), (−1, −1) are received, then the procedure will beexited and the upper layer will be reported to. If (1, 1) is received,then CD-P will be transmitted by using the same power bias. If (1, 0) isreceived, then the CD-P will be transmitted by using the power bias ΔP1.If (0, 1) is received, then CD-P will be transmitted by using the powerbias 2*ΔP1.

If after CD being transmitted by the user equipment and the acquisitionindication for CD-P being received in the down link conflictdetection/channel assignment indication channel (CD/CA-ICH), if it is inT0 set, then the procedure will be exited. If T1 set or T−1 set (basedon the SIGNATURE number for transmitting CD-P, and the same hereinafter)is received, then an acquisition will be indicated. The subsequent powerbias of PCP and the messages will be determined based on the specificvalues of T1 or T−1: when the received indication is (1, 1) or (−1, −1),then PCP and the messages will be transmitted by using the power biasΔPp−m. If the received indication is (1, 0) or (−1, 0), then the PCP andthe messages will be transmitted by using the power bias (ΔPp−m+ΔP1). Ifthe received indication is (0, 1), or (0, −1), then PCP and the messageswill be transmitted by using the power bias (ΔPp−m+2*ΔP1).

1. An access method for variable power adjustment in a code divisionmultiple access mobile communication system, the method being based on abase station and user equipment, comprising: obtaining acquisitioninformation by the base station through receiving via an up link aprefix of a physical random access channel, and an access prefix and aconflict detection prefix of a physical common packet channel andevaluating quality, respectively, the acquisition information beingrepresented by a matrix containing at least two numbers; performingprecise control of transmission power of a message section of thephysical random access channel, and the conflict detection prefix, apower control prefix, and a message section of the physical commonpacket channel being obtained based on quality evaluation valuesobtained from evaluating the quality; transmitting a control indicationof the precise control via an acquisition indication channel, an accessprefix acquisition indication channel, and a conflict detection/channelassignment indication channel of a down link; and after the controlindication being received by the user equipment, transmitting themessage section of the physical random access channel, and the conflictdetection prefix, the power control prefix, and the message section ofthe physical common packet channel by using a value among a plurality ofpower bias values.
 2. An access method as claim 1, wherein, a format ofthe acquisition indication channel and the access prefix acquisitionindication channel that have the control indication of the precisecontrol is:$a_{2k} = {\sum\limits_{s = 0}^{15}\;{{AI}_{1,s}{P_{s}(k)}}}$${a_{{2k} + 1} = {\sum\limits_{s = 0}^{15}\;{{AI}_{2,s}{P_{s}(k)}}}},{k = 0},{{1\mspace{14mu}\ldots\mspace{14mu} 15};}$wherein, Ps(k) is a prefix characteristic code, values of AI₁ and AI₂can be taken as 0, 1, and −1, nine control indications can be producedby combining AI₁ and AI₂.
 3. An access method as claim 1, wherein, aformat of the conflict detection/channel assignment indication channelis:$a_{2l} = {{\sum\limits_{i = 0}^{15}\;{{CDI}_{i,1}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k,1}{P_{Sk}(l)}}}}$${a_{{2l} + 1} = {{\sum\limits_{i = 0}^{15}{{CDI}_{i,2}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k,2}{P_{Sk}(l)}}}}},{1 = 0},{{1\mspace{14mu}\ldots\mspace{14mu} 15};}$wherein, each of CDI₁, CAI₂ can be taken as 0, 1, and −1; definitions ofT₁, T₀, and T⁻¹ being as follows:T₁={(1, 1), (1, 0), (0, 1)};T₀={(0, 0), (1, −1), (−1, 1)};T⁻¹={(−1, −1), (−1, 0), (0, −1)}.
 4. An access method of claim 1,wherein, in power adjustment of the message section of the physicalrandom access channel, when any of acquisition indications of (0, 0),(1, −1), (−1, 1) of acquisition indication channel is received via thedown link, transmitting the prefix of the physical random access channelby continuously using a power bias ΔP0; when any of acquisitionindications of (0, −1), (−1, 0), (−1, −1) is received, exiting theaccess and reporting to an upper layer; when an acquisition indicationof (1, 1) is received, transmitting the message section by using a powerbias ΔPp-m; when an acquisition indication of (1, 0) is received,transmitting the message section by using a power bias ΔPp-m+ΔP1; whenan acquisition indication of (0, 1) is received, transmitting themessage section by using a power bias (ΔPp-m+2*ΔP1).
 5. An access methodof claim 1, wherein, after an acquisition indication of the accessprefix acquisition indication channel is received by the physical commonpacket channel via the down link, when any of acquisition indications of(0, 0), (1, −1), (−1, 1) is received by the user equipment, transmittingthe access prefix by continuously using a power bias ΔP0; when any ofacquisition indications of (0, −1), (−1, 0), (−1, −1) is received,exiting the access and reporting to an upper layer; when an acquisitionindication of (1, 1) is received, transmitting the message section byusing the same power bias; when an acquisition indication of (1, 0) isreceived, transmitting the message section by using a power bias ΔP1;when an acquisition indication of (0, 1) is received, transmitting themessage section by using a power bias (2*ΔP1).
 6. An access method ofclaim 1, wherein, after a transmission power bias indication of theconflict detection/channel assignment indication channel is received bythe physical common packet channel, when the power bias indication fallswithin a T₀ set, exiting the access; when the power bias indicationfalling within a T₁ set or a T⁻¹ set is received, an acquisition isindicated, and transmission power biases of the power control prefix andthe message section are determined by specific values of T₁ or T⁻¹; whenany of power bias indications of (1, 1) or (−1, −1)is received,transmitting the power control prefix and the message section by using apower bias ΔPp-m; when any of power bias indications of (1, 0) or (−1,0) is received, transmitting the power control prefix and the messagesection by using a power bias (ΔPp-m+ΔP1); and when any of power biasindications of (0, 1) or (0, −1) is received, transmitting the powercontrol prefix and the message section by using a power bias(ΔPp-m+2*ΔP1).
 7. An access method for variable power adjustment in acode division multiple access mobile communication system, the methodbeing based on a base station and a user equipment, comprising:obtaining acquisition information by the base station through receivingvia an up link a prefix of a physical random access channel, and anaccess prefix and a conflict detection prefix of a physical commonpacket channel and evaluating quality, respectively; performing precisecontrol of transmission power of a message section of the physicalrandom access channel, and the conflict detection prefix, a powercontrol prefix, and a message section of the physical common packetchannel being obtained based on quality evaluation values obtained fromevaluating the quality; transmitting a control indication of the precisecontrol via an acquisition indication channel, an access prefixacquisition indication channel, and a conflict detection/channelassignment indication channel of a down link; and after the controlindication being received by the user equipment, transmitting themessage section of the physical random access channel, and the conflictdetection prefix, the power control prefix, and the message section ofthe physical common packet channel by using a value among a plurality ofpower bias values, wherein, a format of the acquisition indicationchannel and the access prefix acquisition indication channel that havethe control indication of the precise control is:$a_{2k} = {\sum\limits_{s = 0}^{15}\;{{AI}_{1,s}{P_{s}(k)}}}$${a_{{2k} + 1} = {\sum\limits_{s = 0}^{15}\;{{AI}_{2,s}{P_{s}(k)}}}},{k = 0},{{1\mspace{14mu}\ldots\mspace{14mu} 15};}$wherein, Ps(k) is a prefix characteristic code, values of AI₁ and AI₂can be taken as 0, 1, and −1, nine control indications can be producedby combining AI₁ and AI₂.
 8. An access method for variable poweradjustment in a code division multiple access mobile communicationsystem, the method being based on a base station and a user equipment,comprising: obtaining acquisition information by the base stationthrough receiving via an up link a prefix of a physical random accesschannel, and an access prefix and a conflict detection prefix of aphysical common packet channel and evaluating quality, respectively;performing precise control of transmission power of a message section ofthe physical random access channel, and the conflict detection prefix, apower control prefix, and a message section of the physical commonpacket channel being obtained based on quality evaluation valuesobtained from evaluating the quality; transmitting a control indicationof the precise control via an acquisition indication channel, an accessprefix acquisition indication channel, and a conflict detection/channelassignment indication channel of a down link; and after the controlindication being received by the user equipment, transmitting themessage section of the physical random access channel, and the conflictdetection prefix, the power control prefix, and the message section ofthe physical common packet channel by using a value among a plurality ofpower bias values, wherein, a format of the conflict detection/channelassignment indication channel is:$a_{2l} = {{\sum\limits_{i = 0}^{15}\;{{CDI}_{i,1}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k,1}{P_{Sk}(l)}}}}$${a_{{2l} + 1} = {{\sum\limits_{i = 0}^{15}{{CDI}_{i,2}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\;{{CAI}_{k,2}{P_{Sk}(l)}}}}},{1 = 0},{{1\mspace{14mu}\ldots\mspace{14mu} 15};}$wherein, each of CDI₁, CAI₂ can be taken as 0, 1, and −1; definitions ofT₁, T₀, and T⁻¹ being as follows:T₁ ={(1, 1), (1, 0), (0, 1)};T₀ ={(0, 0), (1, −1), (−1, 1)};T⁻¹ ={(−1, −1), (−1, 0), (0, −1)}.